A wide variety of different electronic devices use a system that both converts internal digital signals to analog signals, and then shifts the frequency of the resultant analog signal. For example, conventional cell phones often have a digital-to-analog converter chip that converts a digitally processed voice signal into an analog baseband signal for transmission. Before transmission, however, a mixer chip shifts the frequency of the baseband signal to a frequency that facilitates transmission.
Use of two or more chips to perform these functions can be inefficient.